In an industrial hydrocracking, the feed may comprise 350-540° C. fraction such as vacuum gas oils (VGO) and the like and the reaction temperature is generally between 350 and 440° C. Components having a higher boiling point in the feed are in a liquid form contacting with catalysts during the reaction. Accordingly, the porous structure of the catalysts is very important. Increasing the pore diameter of the support is needed so as to increase the accessibility of reactant molecules to hydrogenation-active metal within the catalysts. A molecular sieve and metal sulfides have rather small pore volume, and more particular, have less macropores and mesopores which meet the requirements associated with macromolecular hydrocarbon feed required by petroleum processing. It is generally modified by introducing a heat-resistant inorganic oxide matrix with a large pore volume into a hydrocracking catalyst support, such as introducing alumina matrix.
A Chinese patent ZL97121663.0 discloses a hydrocracking catalyst suitable for producing a middle fraction oil, containing an amorphous silica-alumina component and a micropore alumina adhesive as a support and at least one element of the VIB group and at least one element of the VIII group as hydrogenation metals, wherein the amorphous silica-alumina component is in an amount of 30-60 wt %, the total content of the hydrogenation metals is in an range of 20-35 wt % as calculated on oxide and the balance is the micropore alumina adhesive, characterized in that the catalyst has a specific surface of 150-300 m2/g, a pore volume of 0.25-0.50 ml/g, a distribution of the pore having a diameter of 4-15 nm in a range of 60-90% and an infrared acidity of 0.30-0.50 mmol/g.
A Chinese patent ZL01123765.1 discloses a catalyst for hydrotreating diesel oil. The catalyst contains a support, and molybdenum and/or tungsten and nickel and/or cobalt supported on the support, characterized in that the support is consisting of alumina and a zeolite, with a weight-ratio of alumina to the zeolite in a range of 90:10-50:50, wherein the alumina is a composite of a micropore alumina and a macropore alumina in a weight-ratio of 75:25-50:50. The micropore alumina is one wherein the pore volume of the pore having a diameter less than 80 angstrom comprises more than 95% of the total pore volume, while the macropore alumina is one wherein the pore volume of the pore having a diameter of 60-600 angstrom comprises more than 70% of the total pore volume.